IWR6843: Tx and Rx Waveform Polarization

Alex Byrley

Part Number: IWR6843

I have a few questions that I wasn't able to find at answer to in the usual places:

1. What is the default polarization of the Tx waveform? Is it able to be changed?

2. What polarization types are the Rx antennas set up to receive? Is there a way to limit or change the Rx antenna polarization?

Thanks!

over 2 years ago

+1 CHETHAN KUMAR Y.B. over 2 years ago

TI__Mastermind 25835 points

Hello Alex,

Trying to understand your application for this question. What is the reason for this question?

Both Tx and Rx antennas are linearly polarized. It cannot be changed.

However, Tx has binary phase shift modulation where Tx waveform can be flipped by 0 or 180 Deg per chirp basis. Is this something that you are interested?

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Alex Byrley over 2 years ago in reply to CHETHAN KUMAR Y.B.

Intellectual 465 points

Okay -- so this most likely means that they are both linear and vertically polarized. I.e a VV system. Correct?

I am looking into ordering some test fixtures (spherical reflectors vs corner reflectors vs etc) and understanding the polarization of the Tx and Rx antennas will help me to decide which to order given what we are looking to test.

Your reply suggests another question though -- Binary Phase Modulation (BPM) only requires one bit, but you also have a six bit phase shifter in your diagram. Can we, the user, also apply a 6-bit shift? But it comes from somewhere else (i.e. not from the timing engine as the BPM shift suggests), correct?

0 CHETHAN KUMAR Y.B. over 2 years ago in reply to Alex Byrley

TI__Mastermind 25835 points

Hello Alex,

Correct, if you are ordering test fixtures then you may consider corner reflectors

mmWave Production Testing Overview appnote https://www.ti.com/lit/an/spracx7/spracx7.pdf

IWR6843 device would support Binary phase modulation which uses 1 bit and also device supports 6bit linear phase shifter, This introduces finite amount (ex. minimum of 5.6 Deg) phase between the Transmitters, Typically used for Tx beam forming & electronically beam steering applications.

You could refer to below E2E post for the beam forming question

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/759846/iwr6843-question-on-beam-forming

If you want to evaluate this feature you could refer to below long range people counting application.

https://dev.ti.com/tirex/explore/node?node=A__ALa0NkZs5b5KkC0eLj0oEg__radar_toolbox__1AslXXD__LATEST

Thanks and regards,

CHETHAN KUMAR Y.B.

0 Alex Byrley over 2 years ago in reply to CHETHAN KUMAR Y.B.

Intellectual 465 points

Okay great -- so I can either use the 1bit BPM or the 6 bit linear phase shifter, correct?. If so, very cool! I will take a look at the application notes you linked. Thank you!

0 CHETHAN KUMAR Y.B. over 2 years ago in reply to Alex Byrley

TI__Mastermind 25835 points

Alex,

Yes, these i.e. BPM bit and 6 bits phase shifters have independent control.

Thanks and regards,

CHETHAN KUMAR Y.B.

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IWR6843: Tx and Rx Waveform Polarization